#include<stdio.h>
int n, cnt=0;
int main()
{
    scanf("%d", &n);
	while(n)
	{
		int tmp = n%10;
		if(tmp == 7)
			cnt++;
		n /= 10;
	}
	if(cnt == 3)
		printf("good luck!");
	else printf("%d", cnt);
	return 0;
}
